<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script>
        class User{
            constructor(name,pass){
                this.name = name;
                this.pass = pass;
            }

            showName(){
                console.log(this.name)
            }

            showPass(){
                console.log(this.pass)
            }
        }

        class VipUser extends User{
            constructor(name,pass,level){
                super(name,pass);
                this.level = level;
            }

            showLevel(){
                console.log(this.level);
            }
        }

        let vipUser = new VipUser('lan','ee',3);
        vipUser.showName()
        vipUser.showPass()
        vipUser.showLevel()

    </script>
</head>
<body>
    
</body>
</html>